AJP - Endocrinology and Metabolism, Vol 246, Issue 4 339-E343, Copyright © 1984 by American Physiological Society
In vivo stimulation of pancreatic hormone secretion by norepinephrine infusion in the dog
G. Ribes, E. R. Trimble, J. P. Blayac, C. B. Wollheim and M. M. Loubatieres-Mariani
Norepinephrine is generally regarded as an inhibitor of insulin release. It
has been shown, however, that under hyperglycemic circumstances,
norepinephrine infused at a high dose may also stimulate insulin secretion.
The goals of this study were, under normoglycemic conditions, to confirm
this stimulatory effect and to determine whether a beta-adrenergic
mechanism or central neural pathways were involved. Secretion of pancreatic
somatostatin and glucagon were also studied. Fasted, anesthetized dogs had
norepinephrine (2 micrograms X kg-1 X min-1) infused into a peripheral vein
for 60 min; blood was sampled from the pancreaticoduodenal vein.
Norepinephrine stimulated insulin, somatostatin, and glucagon secretion
without significant changes in either blood glucose concentration or
pancreaticoduodenal venous blood flow. The stimulatory effect of
norepinephrine on the three hormones was abolished by propranolol
pretreatment, thus implicating a beta-adrenergic mechanism. Because
bilateral cervical vagotomy prevented stimulation of insulin secretion by
norepinephrine, central neural pathways must have been involved in the
stimulatory process. However, norepinephrine-induced glucagon secretion was
not decreased by vagotomy, showing that the stimulation was due to either a
direct action on the pancreatic A cell or of a central pathway not mediated
via the vagus nerve. Norepinephrine-induced somatostatin secretion was
partly reduced by vagotomy, indicating that several mechanisms could be
implicated.
